Electric furnace



Odi. 31, 1933. o, zlNGG 1,932,567

ELECTRI C FURNACE Filed Sept. l0, 1951 Patented Oct. 31, 193g UNITED STATES ELECTRIC FURNAcE Oskar Zingg, Baden, Switzerland, assigner to Aktiengesellschaft Brown,

Boveri & Cie.,

Baden, Switzerland, a joint stock company Application. September 10, 1931, Serial No. 562,035, and in Switzerland September 16,

4 Claims. (Cl. 13--20) The invention relates to an electrical furnace of cylindrical shape for bulk material, with resistance heating and with traveling grate that is moved lengthwise of the furnace chamber and in which the heating resistances are preferably placed transversely to the direction of travel of the grate. These furnaces are especially suitable for example for splitting up a pulverulent raw material, for instance a salt, into a solid product and a gaseous component in vacuum. The nature of the saltis immaterial, either organic or inorganic salts can be treated, and can be supplied to the furnace by chutes. Heretofore for this purpose use was made of annular furnaces Vwith traveling grates in which the charging and discharging were accomplished. with the aid of special impact or conveying screws. Such furnaces, however, are difficult of access and require a great deal of space. ln addition they present the drawback that pressure must be applied on the material to be treated, this leading to the formation of lumps and making the disintegration difcult.

There are also furnaces with traveling grates made of parts mutually engaging in the manner of chain links in which the separate members form a closed floor which is guided horizontally as an endless belt over conveying rollers at each end of the furnace. Heretofore, however, it was always only the upper section that was used as a grate for conveying the material.

The invention comprises a cylindrical electric furnace for bulk material with resistance heating and traveling grate made of parts engaging with each other in the manner of chain links, its separate members forming a closed floor and being guided horizontally as an endless belt over conveying rollers at the two ends of the furnace, in which the sections of the endless chain running fin opposite directions each form a conveying grate that is charged with the material to be treated through chutes, located at each end of the furnace, and is emptied by the tipping of the table section in the movement over the conveyj ing rollers at the opposite end of the furnace.

In the accompanying drawing one embodiment of the invention is shown diagrammatically, in Fig. 1 in longitudinal section through the furnace and in Fig. 2 in cross-section, two superposed grates being provided. a is the cylindrical body of the furnace which is closed by the end pieces b, b1 in a vacuum-tight and pressuretight manner and is lined with heat-resisting material. The heating resistances c span the "f-furnace chamber transversely and are suitably so `constructed that they can be removed from the furnace chamber during the operation of the furnace without interfering with the conditions in the interior of the furnace. For this purpose they are for instance enclosed in heatresisting tubes which are connected in a vacuum and pressure-tight manner with the furnace shell. The travelling grates d, d1 consist of members which interengage in the manner of the links of a chain and which by the employement of bridging pieces form a closed bottom and are conveyed horizontallyin the form of an endless band over conveyor rollers e, el at the two ends of the furnace. Above, below and between the two stretches of the endless band the heating bodies are mounted. If as in the example shown there are at least two travelling grates consisting of an endless band guided over rollers, vthe row of heating bodies disposed in the space between the two is suitably used for heatingthe two. Each of the chain-like travelling grates is charged on its two upper sides which are conveyed in opposite directions by the conveyor rollers e, el with the material to be treated, by feeding devices through the intermediary of conveyor worms f, fl disposed at the ends of the furnace. The discharge takes place at the opposite ends to the feed, through the separate parts of the grate being caused to tilt as they pass over the conveyor rollers. Preferably for feeding each travelling grate at least two hoppers g, g1 are provided, which are alternately filled and emptied under a vacuum. Similarly there are preferably provided for the treated material two receivers h, h1 to which the finished product is conveyed alternately, one being filled while the other is being emptied. superfluous material is suitably conveyed away by two conveyor Worms and is caught in separate receivers i, il'. f An arrangement (not shown) may also be provided such that superfluous material from the upper grate is conveyed to the grate lying below it, the quantity of material fed to the upper grate being such that the surplus is sufficient for charging the lower grate. K is the passage for conveying away the gaseous product.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A cylindrical electric furnace for bulk materials comprising a furnace shell, a traveling grate assembly in said shell consisting of elements engaging one with the other in the man- `resista'mce elements disposed in heating relation to the material on said grate assembly.

2. A cylindrical electric furnace as denned in claim 1 wherein a plurality o1' traveling grate assemblies are disposed one above the other and certain of the assemblies are driven in. opposite directions.

3. A cylindrical electric furnace as defined in claim l, having two hoppers above the charging end of each ilight of said grate assembly and two receptacles below the discharging end ot each flight of said grate assembly, said hoppers and receptacles being adapted to be alternately iilled and emptied, and vice versa, respectively whereby material may be supplied to and removed from said furnace continuously and without the admission of air into the furnace.

4. A cylindrical electric furnace as defined in claim 1, having means for removing surplus material trom said grate assembly said means includinz a pair of hoppers adapted to be alternately lled and emptied without the admission oi' nir to the furnace.

l OSKAR ZINGG. 

